The present invention relates to an apparatus and method for producing book blocks from a sheet web.
Book blocks and books are traditionally produced using several operational steps. With an apparatus operating with the cylinder printing method, the sheets are imprinted during a first step on the front and on the back according to a specific, predetermined diagram, which makes it possible to arrange successively following pages of the book block in the desired sequence by using suitable and in part very complicated folding operations. When using such a diagram, the page content is not printed in the sequence of the page numbers used for the book block, meaning directly following each other, either side by side or one behind the other, but is printed at different locations on the front and the back of a sheet, so that the pages will be in the corresponding sequence only at the conclusion of the aforementioned folding operations. The pages are initially still connected via the folds and need to be separated in a subsequent, special trimming step, among other things in a three-way trimming operation using a so-called three-way trimmer.
As a result of the holding capacity for different page contents, which is restricted to the printing cylinder circumference and width, a make ready of the printing cylinder is generally required several times for a book block having a higher number of different pages, wherein the cylinder is provided each time with the print image of a group containing the content of the still missing pages and the sheets must then be printed accordingly and folded once more in a subsequent folding operation. As an alternative, it is also possible to use several printing cylinders matched to the respective group. The groups formed in this way are initially stored in an intermediate storage area, which requires a corresponding amount of storage space. After all the groups have been printed, the pages of each group are folded according to the previously mentioned diagram, in most cases during several folding operations, and the individual groups are then gathered in the folded form into book blocks that are subsequently trimmed and bound. To be sure, the cylinder printing methods result in high-quality print, but they are relatively involved and require a complex storing logistic with corresponding storage capacity. Installations that use the cylinder printing method are furthermore restricted to a few formats which depend on the printing cylinder geometry. Frequently, a format change also requires a change in the printing cylinder geometry. Finally, empty pages are in part also required in dependence on the selected page number, which necessitate correspondingly empty surface sections on the printing cylinder, thereby reducing the effectiveness of the printing cylinder.
A method and an apparatus for the production of paper bundles is known from German patent document DE 26 32 712 A1, for which an endless paper web of a multiple bundle width is imprinted on both sides with repeating rows of different types of printing images with the aid of printing cylinders, is then separated by cutting it in a longitudinal direction into several partial webs. The partial webs are then cut in a transverse direction into individual sheets and the sheets from two adjacent partial webs are then collected by placing them one above the other in a transfer device. This known apparatus also operates with the rather inflexible use of printing cylinders, as well as with the rather time-intensive collecting operation.